A standard single-lever flow-control valve has a fixed valve plate formed with a pair of input ports respectively connected to hot- and cold-water input lines and, offset therefrom, an output port connected to an output line normally leading to a faucet. A movable valve plate sitting atop this fixed valve plate has a mixing cavity open toward the fixed plate and movable to variously overlap the ports. When the movable plate is pivoted about a normally upright axis perpendicular to the interface between the plates it can align more of one of the input ports with the mixing cavity and less of the other inlet port to vary the ratio of hot and cold water fed to the outlet port, and when slid in a front-to-back direction parallel to the plate interface it can control the overall extent of overlap to vary the overall flow from the inlet ports through the mixing cavity to the outlet port.
Typically the movable valve plate is pivoted on the bottom end of a lever that is centrally pivoted on a housing liner that is coupled to the movable plate to rotate it about the upright axis. The upper end of the lever is fitted to a handle that is raised and lowered to control volume rate of flow and that is pivoted from side to side to control output temperature.
As described in German patent documents 3,719,410 filed 11 Jun. 1987 by H. Buckel and 3,822,217 filed 1 Jul. 1988 by H. Oberdorfer, it is known to provide such a valve with a stop that limits movement of the lever along the path it travels to control flow rate. The purpose is to prevent the faucet from being turned on full, thereby wasting water. The stop is elastically deflectable so that the user can push the lever past it and thereby get full flow.
The problem with the known arrangements is that the stop system is provided in the valve cartridge immediately adjacent the lever pivot axis. Thus in order for the overridable stops to be effective they must bear with considerable force on the lever. As a result they are subjected to substantial friction and wear.
Another disadvantage of the known systems is that they must be built in at the factory. There is no chance for the installer to change or reset the stops.